Record Collapse of Earth's Upper Atmosphere Puzzles Scientists

By SPACE.com Staff
15 July 2010
Graphic: John Emmert

An upper layer of Earth's atmosphere recently collapsed in an unexpectedly large contraction, the sheer size of which has scientists scratching their heads, NASA announced Thursday.

The layer of gas – called the thermosphere – is now rebounding again. This type of collapse is not rare, but its magnitude shocked scientists.

"This is the biggest contraction of the thermosphere in at least 43 years," said John Emmert of the Naval Research Lab, lead author of a paper announcing the finding in the June 19 issue of the journal Geophysical Research Letters. "It's a Space Age record."

The collapse occurred during a period of relative solar inactivity – called a solar minimum from 2008 to 2009. These minimums are known to cool and contract the thermosphere, however, the recent collapse was two to three times greater than low solar activity could explain. "Something is going on that we do not understand," Emmert said.

ISO considers potential standard on water footprint

ISO is considering the development of a new standard to provide internationally harmonized metrics for water footprints.

by Mélanie Raimbault and Sebastien Humbert *

Currently at the stage of a Preliminary Work Item (PWI), ISO 14046, Water footprint – Requirements and guidelines, would complement existing standards on life cycle assessment (LCA) and ongoing work on carbon footprint metrics by ISO technical committee ISO/TC 207, Environmental management. It would also take into account the ISO 14064 standards on the accounting and verification of greenhouse gases (GHG).

ISO/PWI 14046 is being studied by the new working group WG 8 set up by ISO/TC 207 subcommittee SC 5, Life cycle assessment.

At its first meeting, WG 8 proposed a scope for the standard as specifying "requirements and guidelines to assess and report water footprints based on LCA". The standard would: